Understanding NEWS 9 weather radars

Thursday, December 13th 2007, 11:46 am
By: News 9

MOAR Radar (Massive Output Arrayed Radar) is a "live" radar owned and operated by NEWS 9 in Oklahoma City. This high resolution radar allows our staff of meteorologists to control the radar, the sweep and the tilt of the radar beam.  It operates in the C-band range and returns intensity (precipitation rates) and velocity (direction and speed the precipitation particles) data utilizing a 14-foot antenna with a peak power of 250 Kilowatts.

MOAR Radar is a high resolution radar that provides a much higher quality radar picture due to the increased sampling rate of the processor. The system is capable of sampling radar intensity data every 150 meters in range and every 0.08 degrees in azimuth while operating through the radar's full range. That sampling rate is 12 times higher than NEXRAD.  This high resolution allows for greater detail of radar images and allows our staff to better analyze the severe potential of thunderstorms including tornadoes.

MOAR is particularly beneficial when identifying potentially tornadic circulations due to the increased sampling rate, the functionality of operating our own live radar and the experience of our meteorologists.

Like all radars, the Next Generation Radar or NEXRAD obtains weather information based on returned energy. The radar emits a burst of energy. If the energy strikes an object (precipitation), the energy is scattered in all directions. A small fraction of that energy is scattered back to the radar. This signal is then received by the radar during its listening period. Computers analyze the strength of the returned pulse, time it took to travel to the object and back, and phase shift of the pulse. This process happens up to 1,300 times a second.

Radar spends the vast amount of time "listening" for returning signals it sent. When the time of all the pulses each hour is totaled, the radar is "on" for about seven seconds each hour. The remaining 59 minutes and 53 seconds are spent listening for any returned signals.

The most promising NEWS 9 radar on line right now is ESP - Early Storm Protection radar.  This system uses Level II NEXRAD radar data.  Special algorithms provide stunning and highly accurate information on severe storms and tornadoes to our staff and to the viewing public.  For example, the risk of a tornado increases dramatically when the Mesocyclone scale goes above the number 5,000 along with a probability rating greater than 30%.  Using such information along with the highly detailed MOAR presentations allows our meteorologists to provide more timely and more accurate warnings.

Types of Radar Images

Base Reflectivity
This is a display of reflectivity measured in decibels of Z, where Z represents the energy reflected back to the radar. Reflectivity is the amount of transmitted power returned to the radar receiver.

Composite Reflectivity
This display is of maximum reflectivity from any elevation angle at every range from the radar. This product is used to reveal the highest reflectivity in all echoes.

One Hour Precipitation
This is an image of estimated one-hour precipitation accumulation on a 1.1 nm by 1 degree grid. This product is used to assess rainfall intensities for flash flood warnings, urban flood statements and special weather statements.

Storm Total Precipitation
This image is of estimated accumulated rainfall, continuously updated, since the last one hour break in precipitation. This product is used to locate flood potential over urban or rural areas, estimate total basin runoff and provide rainfall accumulations for the duration of the event.

To view Doppler Radars across the nation visit National Doppler Radar Sites.